The automotive industry has turned to the use of padded-safety trim components comprising a polyvinyl chloride spaced from a metal or rigid plastic insert wherein the space between is filled with a urethane foam that is foamed in place to give a well-bonded integral structure. See, for example, the trim components disclosed in U.S. Pat. No. 3,123,403. The acceptance of such components has been because inter alia this type of padded construction permits a wide latitude in styling and color, and grain effects which are most desired particularly in the interior design of automobiles. To provide well matched color and grain, it is desirable to use the same polyvinyl chloride skin materials in surrounding and adjacent parts where padding is not needed.
The current state of the art includes loading a pre-formed grained vinyl shell in an ungrained mold of aluminum or epoxy construction and pouring reaction injection molding material or reinforced injection molding material of urethane or other compositions directly behind the shell to form an integral rigid substrate which is strongly bonded to the grained vinyl shell and which supports the shell thereby providing an unpadded article that matches the adjacent padded articles but at lower cost. The process can result in flattening of the grained face of the vinyl shell due to pressure and exotherm heat developed during the reaction injection molding action.
Other processes use a mold made from silicone or urethane materials with a hardness in the range of 60-90 shore A. These molds are cast with pre-formed grained relief to create a grain in the outer surface of micro-cellular urethane moldings. This type of mold is employed without a vinyl shell or skin.